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用第 3～ 5周人胚 ,石蜡切片 ,免疫组化染色 ,光镜下观察人胚肝的细胞特征和HGF、IGF -I、TGFβ1等生长因子及其受体、PCNA、AFP、CK19等的表达。结果发现第 3周末肝芽形成 ,第 4周肝索开始形成 ,第 3～ 4周人胚肝由同一类具有幼稚细胞形态学特征的细胞构成。这些细胞为AFP、c Met阳性反应。第 5周时肝索细胞的数量增加 ,开始出现PCNA的表达 ,仍仅为同一类细胞。第 5周肝索细胞呈IGF -I、TGFβ1及其受体免疫反应阳性 ,HGF阴性 ,其周围的心肌细胞及间充质细胞为HGF阳性反应。结果提示第 3～ 5周 ,组成肝芽和肝索的细胞属于肝干细胞 ,其形态和因子表达的差异说明肝干细胞可能处于不同的发育阶段 ,AFP、c Met可以作为此阶段肝干细胞的标记物 ,HGF、IGF -I、TGFβ1及其受体可能参与对早期人胚肝发育的调节。
Cell characteristics of human embryonic liver and growth factors such as HGF, IGF-I, TGFβ1 and their receptors, PCNA, AFP, CK19 and so on were observed with human embryo, paraffin section, immunohistochemical staining and light microscope expression. The results showed that liver buds formed on the third weekend, and hepatic cord began to form on the fourth week. The third to fourth weeks’ embryonic liver consisted of the same type of cells with morphological features of naive cells. These cells are AFP positive for c Met. At the fifth week, the number of hepatic cells increased, PCNA began to appear, still only the same type of cells. In the fifth week, hepatic cord cells showed positive immunoreactivity of IGF-I, TGFβ1 and their receptors, and negative HGF. Cardiomyocytes and mesenchymal cells around them were positive for HGF. The results suggest that the cells from liver buds and hepatic cords belong to hepatic stem cells from the 3rd to 5th week, and the difference of their morphological and factor expression indicates that hepatic stem cells may be in different developmental stages. AFP and c Met can be used as markers of hepatic stem cells in this stage , HGF, IGF-I, TGFβ1 and their receptors may be involved in the regulation of early human embryonic liver development.